What volume would 3 moles of hydrogen gas occupy at stp?

22.4 LSo, if 1 mole occupies 22.4 L, the imediate conclusion is that a bigger number of moles will occupy more than 22.4 L, and a smaller number of moles will occupy less than 22.4 L. In your case, 3 moles of gas will occupy 3 times more volume than 1 mole of gas.

Ametal with a large number of free flowing electrons most likely has good conductivity

It will appear as o2(g) as a reactant